The active site of snake venom phospholipase A2 will be located with substrate analog photoaffinity labels. Snake pancreas and venom glands will be examined for the presence of phospholipase and phospholipase precursors. Homogeneous preparations of juvenile hormone carrier protein and juvenile hormone specific esterase from the tobacco hornworm, Manduca sexta, will be characterized. Antibodies will be prepared to each protein for radioimmune assay and radioactive labeled proteins will also be used to study their mutual interaction as well as interaction with hormone target tissue. The purification and chemisty of the egg yolk protein and its precursor in M. sexta will be explored.